Lipid core-shell nanoparticles co-deliver FOLFOX regimen and siPD-L1 for synergistic targeted cancer treatment.

FOLFOX regimen, composed of folinic acid, 5-fluorouracil (5-FU) and oxaliplatin (OXP), has been used as clinical standard therapeutic regimen in treatments of colorectal cancer (CRC) and esophageal squamous cell carcinoma (ESCC). To further improve its therapeutic outcomes, FOLFOX was combined with anti-PD-1 antibody to form an advanced chemo-immune combination strategy, which has been proven more efficient in controlling cancer progression and prolonging patients' survival in various clinical trials. However, bad tumor accumulation, relative high toxicity, numerous treatment cycles with high fees and low compliance as well as drug resistance seriously limit the prognosis of FOLFOX regimen. The "all-in-one" formulations, which could precisely delivery multidrug regimen into tumor sites and cells, showed a promising application prospect for targeted drug delivery as well as reducing side effects. However, the design and preparation of the "all-in-one" formulation with high drug encapsulation efficiencies for all drugs was still challenging. Herein, a lipid core-shell nanoparticle codelivery platform was designed for simultaneous encapsulation of variant FOLFOX composed of miriplatin (MiPt), 5-Fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP), calcium folinate (CF) and PD-L1 siRNA (siPD-L1) with high efficiencies, and their synergistic anti-tumor mechanisms were studied, respectively. MiPt, a precursor of OXP, was validated capable of inducing efficient immunogenic cell death (ICD) in this work. Additionally, ICD-mediated release of damage associated molecular patterns functionalized synergistically with PD-L1 silence by siPD-L1 to overcome chemoresistance, reverse suppressive tumor microenvironment and recruit more CD8 T cells. FdUMP, as the intracellular active form of 5-FU, could induce large amounts of reactive oxygen species to enhance the ICD. CF worked as the sensitizer of FdUMP. The enhanced long-term anti-tumor effect of the prepared "all-in-one" formulation compared to free drug regimen and other controls, was verified in heterotopic CRC mice models and ESCC mice models, providing new thoughts for researchers and showing a promising prospect of translation into clinical applications.